ʻAkiapōlāʻau

ʻAkiapōlāʻau
United States Fish and Wildlife Service · Public domain · source
Name	ʻAkiapōlāʻau
Status	CR
Status system	IUCN3.1
Genus	Hemignathus
Species	wilsoni
Authority	(Rothschild, 1892)

ʻAkiapōlāʻau is a critically endangered Hawaiian honeycreeper endemic to the island of Hawaii (island), known for its distinctive asymmetrical bill used for foraging. It is a culturally significant species in Hawaiian language and has been the subject of conservation efforts by organizations including the U.S. Fish and Wildlife Service, Hawaii Department of Land and Natural Resources, and non-governmental groups such as the Hawaiian Honeycreeper Recovery Team. The species has drawn attention from ornithologists at institutions like the Bishop Museum, the University of Hawaiʻi at Mānoa, and the Smithsonian Institution.

Taxonomy and Etymology

Described by Lionel Walter Rothschild in 1892, the species was placed in the genus Hemignathus within the family Fringillidae, reflecting relationships with other Hawaiian honeycreepers such as ʻAkohekohe, Palila, and Iiwi. Molecular studies involving researchers from the American Museum of Natural History and the University of California, Berkeley have placed Hemignathus species in a clade with genera like Loxioides and Telespiza. The common name derives from ʻākia (a Hawaiian shrub) and polālāʻau (to pick or strip wood), terms rooted in Hawaiian culture and the Hawaiian language; the scientific epithet honors ornithologist Scott Barchard Wilson.

Description

The ʻAkiapōlāʻau exhibits sexual dimorphism: males display olive-green upperparts and bright yellow underparts while females are duller, similar to patterns seen in Maui parrotbill and Akiapolaau records held by museums such as the Natural History Museum, London. Its unique bill combines a short, stout lower mandible and a long, curved upper mandible, functionally convergent with bills of species like the crossbills and the extinct ʻŌʻū. Adult length and mass measurements have been recorded in field studies by teams from USGS and Hawaiʻi Forest Institute. Plumage descriptions have been published in monographs by the American Ornithological Society and field guides produced by the Audubon Society.

Distribution and Habitat

Historically restricted to high-elevation mesic and wet forests on Hawaii Volcanoes National Park and surrounding areas on Mauna Kea, Mauna Loa, and Hualālai slopes, current populations occupy fragmented remnant forests dominated by native trees such as ohia lehua (Metrosideros polymorpha), koa (Acacia koa), and māmane (Sophora chrysophylla analogs). Surveys conducted by teams from the U.S. Fish and Wildlife Service and the Hawaiʻi Division of Forestry and Wildlife have documented occupancy in pockets of Kipuka Puaulu and kahakuloa zones, often overlapping with conservation lands managed by The Nature Conservancy and Kamehameha Schools. Elevational range typically exceeds 1,000 meters, similar to distributions of Honeycreeper relatives and other endemics like Nēnē and Kākā.

Behavior and Ecology

The species is an obligate insectivore and nectarivore, employing its specialized bill to probe bark and epiphytes for insect larvae and to extract nectar from flowers of Metrosideros and other native genera, paralleling foraging behaviors documented for Hawaiian honeycreepers such as Iiwi and Apapane. Field observations by researchers affiliated with University of California, Santa Cruz and Hawaiʻi Pacific University describe gleaning, probing, and bark-stripping behaviors, with foraging strata occupying mid to upper canopy layers similar to ʻAmakihi. Interactions occur with introduced species like Rats (Rattus), Cats (Felis catus), and avian competitors including Japanese White-eye (Zosterops japonicus), with disease dynamics influenced by avian malaria and vectors like the southern house mosquito (Culex quinquefasciatus), studied by entomologists at Centers for Disease Control and Prevention and University of Hawaiʻi.

Reproduction and Lifespan

Breeding phenology follows patterns recorded for other Hawaiian passerines, with nest construction in native canopies using materials documented by National Audubon Society and researchers at the Hawaiian Ecosystems at Risk Project. Clutch size, incubation period, and fledging success have been estimated in longitudinal studies by the U.S. Geological Survey and conservation biologists from Sierra Club-affiliated projects, though sample sizes remain small due to low population density. Lifespan in the wild is uncertain but comparisons with related species such as Palila suggest multi-year survival under low disease and predation pressure; captive care protocols have been developed in coordination with the San Diego Zoo and the Smithsonian National Zoo for emergency management.

Conservation Status and Threats

Listed as Critically Endangered by the IUCN and protected under the Endangered Species Act, the species faces threats from habitat loss due to invasive plants like Miconia calvescens and Hawaiian weed incursions, introduced predators, and avian malaria facilitated by climate change and warming elevational limits studied by climate researchers at NOAA and IPCC-related institutions. Recovery actions involve habitat restoration by Plant Extinction Prevention Program, disease management research by teams at the University of Hawaiʻi at Mānoa and Johns Hopkins University, and biosecurity measures coordinated with U.S. Fish and Wildlife Service and Hawaiʻi Department of Agriculture. Captive propagation, translocation, and predator control have been trialed in collaboration with Kupu and international partners including the Royal Society for the Protection of Birds. Continued monitoring uses methods standardized by the Partners in Flight network and relies on funding mechanisms from agencies such as the National Science Foundation and philanthropic foundations like the Packard Foundation.

Category:Hemignathus Category:Endemic birds of Hawaii